ASP.net ,C#, VB.net and COM -Full of Microsoft Technology

8/6/2019 ASP.net ,C#, VB.net and COM -Full of Microsoft Technology

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ASP.NET ,C#, VB.NET and

COM etc.Full of microsoft Technology

What is view state and use of it?The current property settings of an ASP.NET page and those of any ASP.NET server controlscontained within the page. ASP.NET can detect when a form is requested for the first time versuswhen the form is posted (sent to the server), which allows you to program accordingly.

What are user controls and custom controls?Custom controls:A control authored by a user or a third-party software vendor that does not belong to the .NET

Framework class library. This is a generic term that includes user controls. A custom server control is used in Web Forms (ASP.NET pages). A custom client control is used in WindowsForms applications.

User Controls:In ASP.NET: A user-authored server control that enables an ASP.NET page to be re-used as aserver control. An ASP.NET user control is authored declaratively and persisted as a text filewith an .ascx extension. The ASP.NET page framework compiles a user control on the fly to aclass that derives from the System.Web.UI.UserControl class.

What are the validation controls?A set of server controls included with ASP.NET that test user input in HTML and Web server controls for programmer-defined requirements. Validation controls perform input checkingin server code. If the user is working with a browser that supports DHTML, the validation controlscan also perform validation using client script.

What's the difference between Response.Write() andResponse.Output.Write()?Ans: The latter one allows you to write formattedoutput.

ExampleResponse.Write(Hello {0},DateTime.Now.ToString()); //Will lead to Compile time error Response.Output.Write(Hello {0},DateTime.Now.ToString()); //Will work fine

What methods are fired during the page load? Init()PageInit, PageLoad, PagePreRender, Page Unload

Where does the Web page belong in the .NET Framework class hierarchy?System.Web.UI.Page

What's a bubbled event?When you have a complex control, likeDataGrid, writing an event processing routine for each object (cell, button,row, etc.) is quite tedious. The controls can bubble uptheir eventhandlers, allowing the main DataGrid event handler to take care of its constituents.Suppose you want a certain ASP.NET function executed on MouseOver over a certain button.

Where do you add an event handler?It's the Attributesproperty, the Add function inside that property.e.g. btnSubmit.Attributes.Add("onMouseOver","someClientCode();")

What data type does the RangeValidator control support?Integer,String and Date.

What are the different types of caching?

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Caching is a technique widely used in computing to increase performance bykeeping frequently accessed or expensive data in memory. In context of web application, cachingis used to retain the pages or data across HTTP requests and reuse them without the expenseof recreating them.ASP.NET has 3 kinds of caching strategiesOutput CachingFragmentCachingData

CachingOutput Caching: Caches the dynamic output generated by a request. Some times itis useful to cache the output of a website even for a minute, which will result in a

better performance. For caching the whole page the page should have OutputCache directive.

Fragment Caching: Caches the portion of the page generated by the request. Some times it isnot practical to cache the entire page, in such cases we can cache a portion of page

Data Caching: Caches the objects programmatically. For data caching asp.net provides acache object for eg: cache["States"] = dsStates;

What do you mean by authentication and authorization?Authentication is the process of validating a user on the credentials (username and password)and authorization performs after authentication. After Authentication a user will be verified for

performing the various tasks, It access is limited it is known as authorization.

What are different types of directives in .NET?@Page : Defines page-specific attributes used by the ASP.NET page parser and compiler. Can

be included only in .aspx files @Control :Defines control-specific attributes used by the ASP.NET page parser andcompiler. Can be included only in .ascx files. @Import : Explicitly imports a namespace into a page or user control. The Import directivecannot have more than one namespace attribute. To import multiple namespaces, usemultiple @Import directives. @Implements : Indicates that the current page or user control implements the specified .NETframework interface.

@Register : Associates aliases with namespaces and class names for concise notation incustom server control syntax.@Assembly : Links an assembly to the current page during compilation, making all theassembly's classes and interfaces available for use on the page. @OutputCache : Declaratively controls the output caching policies of an ASP.NET page or auser control contained in a page@Reference : Declaratively indicates that another user control or page source file shouldbe dynamically compiled and linked against the page in which this directive is declared.

How do I debug an ASP.NET application that wasn't written with Visual Studio.NET andthat doesn't use code-behind?Start the DbgClr debugger that comes with the .NET Framework SDK, open the file containingthe code you want to debug, and set your breakpoints. Start the ASP.NET application. Go back toDbgClr, choose Debug Processes from the Tools menu, and select aspnet_wp.exe from the listof processes. (If aspnet_wp.exe doesn't appear in the list,check the "Show system processes"box.) Click the Attach button to attach to aspnet_wp.exe and begin debugging.Be sure to enable debugging in the ASPX file before debugging it with DbgClr. You can enabletell ASP.NET to build debug executables by placing a statement at the top of an ASPX file or a statement in a Web.config file. Can a user browsing my Web site read my Web.config or Global.asax files?

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No. The section of Machine.config, which holds the master configuration settings for ASP.NET, contains entries that map ASAX files, CONFIG files, andselected other file types to an HTTP handler named HttpForbiddenHandler, which fails attemptsto retrieve the associated file. You can modify it by editing Machine.config or including an sectionin a local Web.config file.

What's the difference between Page.RegisterClientScriptBlock andPage.RegisterStartupScript?

RegisterClientScriptBlock is for returning blocks of client-side script containing functions.RegisterStartupScript is for returning blocks of client-script not packaged in functions-in other words, code that's to execute when the page is loaded. The latter positions script blocks near theend of the document so elements on the page that the script interacts are loaded before the scriptruns.

Is it necessary to lock application state before accessing it?Only if you're performing a multistep update and want the update to be treated as an atomicoperation. Here's an example:

Application.Lock ();Application["ItemsSold"] = (int) Application["ItemsSold"] + 1;Application["ItemsLeft"] = (int) Application["ItemsLeft"] - 1;Application.UnLock ();

By locking application state before updating it and unlocking it afterwards, you ensure thatanother request being processed on another thread doesn't read application state at exactly thewrong time and see an inconsistent view of it. If I update session state, should I lock it, too? Areconcurrent accesses by multiple requests executing on multiple threads a concern with sessionstate?Concurrent accesses aren't an issue with session state, for two reasons. One, it's unlikely thattwo requests from the same user will overlap. Two, if they do overlap, ASP.NET locks downsession state during request processing so that two threads can't touch it at once. Session stateis locked down when the HttpApplication instance that's processing the request fires anAcquireRequestState event and unlocked when it fires a ReleaseRequestState event.

Do ASP.NET forms authentication cookies provide any protection against replay attacks? Dothey, for example, include the client's IP address or anything else that would distinguish the realclient from an attacker?No. If an authentication cookie is stolen, it can be used by an attacker. It's up to you to preventthis from happening by using an encrypted communications channel (HTTPS). Authenticationcookies issued as session cookies, do, however,include a time-out valid that limits their lifetime. So a stolen session cookie can only be used in replay attacks as long as the ticket insidethe cookie is valid. The default time-out interval is 30 minutes.You can change that by modifyingthe timeout attribute accompanying the element in Machine.config or a local Web.configfile. Persistent authentication cookies do not time-out and therefore are a more serious securitythreat if stolen.

How do I send e-mail from an ASP.NET application?

MailMessage message = new MailMessage ();message.From = ;message.To = ;message.Subject = "Scheduled Power Outage";message.Body = "Our servers will be down tonight.";SmtpMail.SmtpServer = "localhost";SmtpMail.Send (message);

MailMessage and SmtpMail are classes defined in the .NET Framework Class Library'sSystem.Web.Mail namespace. Due to a security change made to ASP.NET just before itshipped, you need to set SmtpMail's SmtpServer property to "localhost" even though "localhost"is the default. In addition, you must use the IIS configuration applet to enable localhost(127.0.0.1) to relay messages through the local SMTP service.

What are VSDISCO files?

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Application_ReleaseRequestState, Application_ResolveRequestCache,Application_UpdateRequestCache, Session_Start,Session_EndYou can optionally include "On" in any of method names. For example, you can name aBeginRequest event handler.Application_BeginRequest or Application_OnBeginRequest.You canalso include event handlers in Global.asax for events fired by custom HTTP modules.Note thatnot all of the event handlers make sense for Web Services (they're designed for ASP.NETapplications in general, whereas .NET XML Web Services are specialized instances of anASP.NET app). For example, the Application_AuthenticateRequest and

Application_AuthorizeRequest events are designed to be used with ASP.NET Formsauthentication.

What is different b/w webconfig.xml & Machineconfig.xmlWeb.config & machine.config both are configuration files.Web.config contains settings specific toan application where as machine.config contains settings to a computer. The Configurationsystem first searches settings in machine.config file & then looks in application configurationfiles.Web.config, can appear in multiple directories on an ASP.NET Web application server. EachWeb.config file applies configuration settings to its own directory and all child directories below it.There is only Machine.config file on a web server.

If I'm developing an application that must accomodate multiple security levels though secure loginand my ASP.NET web appplication is spanned across three web-servers (using round-robbin

load balancing) what would be the best approach to maintain login-in state for the users?Use the state server or store the state in the database. This can be easily done through simplesetting change in the web.config.

You can specify mode as stateserver or sqlserver.

Where would you use an iHTTPModule, and what are the limitations of any approach you might

take in implementing one"One of ASP.NET's most useful features is the extensibility of the HTTP pipeline, the path thatdata takes between client and server. You can use them to extend your ASP.NET applications byadding pre- and post-processing to each HTTP request coming into your application. For example, if you wanted custom authentication facilities for your application, the best techniquewould be to intercept the request when it comes in and process the request in a custom HTTPmodule.

How do you turn off cookies for one page in your site?Since no Page Level directive is present, I am afraid that cant be done.

How do you create a permanent cookie?Permanent cookies are available until a specified expiration date, and are stored on the harddisk.So Set the 'Expires' property any value greater than DataTime.MinValue with respect to thecurrent datetime. If u want the cookie which never expires set its Expires property equal toDateTime.maxValue.

Which method do you use to redirect the user to another page without performing a roundtrip to the client?Server.Transfer and Server.Execute

What property do you have to set to tell the grid which page to go to when using the Pager object?CurrentPageIndex

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Should validation (did the user enter a real date) occur server-side or client-side? Why?

It should occur both at client-side and Server side.By using expression validator control with thespecified expression ie.. the regular expression provides the facility of only validatating the datespecified is in the correct format or not. But for checking the date where it is the real data or notshould be done at the server side, by getting the system date ranges and checking the datewhether it is in between that range or not.

What does the "EnableViewState" property do? Why would I want it on or off?Enable ViewState turns on the automatic state management feature that enables server controlsto re-populate their values on a round trip without requiring you to write any code. This feature isnot free however, since the state of a control is passed to and from the server in a hidden formfield. You should be aware of when ViewState is helping you and when it is not. For example, if you are binding a control to data on every round trip, then you do not need the control to maintainit's view state, since you will wipe out any re-populated data in any case. ViewState is enabled for all server controls by default. To disable it, set the EnableViewState property of the control tofalse.

What is the difference between Server.Transfer and Response.Redirect? Why would Ichoose one over the other?Server.Transfer() : client is shown as it is on the requesting page only, but the all the content is of

the requested page. Data can be persist accros the pages using Context.Item collection, which isone of the best way to transfer data from one page to another keeping the page state alive.

Response.Dedirect() :client know the physical location (page name and query string as well).Context.Items loses the persisitance when nevigate to destination page. In earlier versions of IIS,if we wanted to send a user to a new Web page, the only option we had was Response.Redirect.While this method does accomplish our goal, it has several important drawbacks. The biggestproblem is that this method causes each page to be treated as a separate transaction. Besidesmaking it difficult to maintain your transactional integrity, Response.Redirect introduces someadditional headaches. First, it prevents good encapsulation of code. Second, you lose access toall of the properties in the Request object. Sure, there are workarounds, but they're difficult.Finally, Response.Redirect necessitates a round trip to the client, which, on high-volume sites,causes scalability problems. As you might suspect, Server.Transfer fixes all of these problems. It

does this by performing the transfer on the server without requiring a roundtrip to the client.

Can you give an example of when it would be appropriate to use a web service as opposedto a non-serviced .NET component?

Communicating through a Firewall When building a distributed application with100s/1000s of users spread over multiple locations, there is always the problem of communicating between client and server because of firewalls and proxy servers.Exposing your middle tier components as Web Services and invoking the directly from aWindows UI is a very valid option.

Application Integration When integrating applications written in various languages andrunning on disparate systems. Or even applications running on the same platform thathave been written by separate vendors.

Business-to-Business Integration This is an enabler for B2B intergtation which allows oneto expose vital business processes to authorized supplier and customers. An examplewould be exposing electronic ordering and invoicing, allowing customers to send youpurchase orders and suppliers to send you invoices electronically.

Software Reuse This takes place at multiple levels. Code Reuse at the Source code levelor binary componet-based resuse. The limiting factor here is that you can reuse the codebut not the data behind it. Webservice overcome this limitation. A scenario could be whenyou are building an app that aggregates the functionality of serveral other Applicatons.Each of these functions could be performed by individual apps, but there is value inperhaps combining the the multiple apps to present a unifiend view in a Portal or Intranet.

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When not to use Web Services: Single machine Applicatons When the apps arerunning on the same machine and need to communicate with each other use a nativeAPI. You also have the options of using component technologies such as COM or .NETComponets as there is very little overhead.

Homogeneous Applications on a LAN If you have Win32 or Winforms apps that want tocommunicate to their server counterpart. It is much more efficient to use DCOM in thecase of Win32 apps and .NET Remoting in the case of .NET Apps

Can you give an example of what might be best suited to place in the Application_Startand Session_Start subroutines?The Application_Start event is guaranteed to occur only once throughout the lifetime of theapplication. It's a good place to initialize global variables. For example, you might want to retrievea list of products from a database table and place the list in application state or the Cache object.SessionStateModule exposes both Session_Start and Session_End events.

What are the advantages and disadvantages of viewstate?The primary advantages of the ViewState feature in ASP.NET are:

1. Simplicity. There is no need to write possibly complex code to store form data between pagesubmissions.2. Flexibility. It is possible to enable, configure, and disable ViewState on a control-by-controlbasis, choosing to persist the values of some fields but not others.

There are, however a few disadvantages that are worth pointing out:

1. Does not track across pages. ViewState information does not automatically transfer from pageto page. With the sessionapproach, values can be stored in the session and accessed from other pages. This is notpossible with ViewState, so storingdata into the session must be done explicitly.

2. ViewState is not suitable for transferring data for back-end systems. That is, data still has to betransferred to the backend using some form of data object.

Describe session handling in a webfarm, how does it work and what are the limits?ASP.NET Session supports storing of session data in 3 ways, i] in In-Process ( in the samememory that ASP.NET uses) , ii] out-of-process using Windows NT Service )in separate memoryfrom ASP.NET ) or iii] in SQL Server (persistent storage). Both the Windows Service and SQLServer solution support a webfarm scenario where all the web-servers can be configured to sharecommon session state store. 1. Windows Service :We can start this service by Start | Control Panel | Administrative Tools | Services | . In that weservice names ASP.NET State Service. We can start or stop service by manually or configure tostart automatically. Then we have to configure our web.config file

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Here ASP.Net Session is directed to use Windows Service for state management onlocal server (address : 127.0.0.1 is TCP/IP loop-back address). The default port is 42424. we canconfigure to any port but for that we have to manually edit the registry.Follow these simple steps

- In a webfarm make sure you have the same config file in all your web servers.- Also make sure your objects are serializable.- For session state to be maintained across different web servers in the webfarm, the applicationpath of the web-site in the IIS Metabase should be identical in all the web-servers in the webfarm.

Which template must you provide, in order to display data in a Repeater control?You have to use the ItemTemplate to Display data. Syntax is as follows,

< ItemTemplate >< div class =rItem >

< img src=images/ hspace=10 />< b >

< /div >< ItemTemplate >

How can you provide an alternating color scheme in a Repeater control?Using the AlternatintItemTemplate

What property must you set, and what method must you call in your code, in order to bindthe data from some data source to the Repeater control?Set the DataMember property to the name of the table to bind to. (If this property is not set, bydefault the first table in the dataset is used.)DataBind method, use this method to bind data from a source to a server control. This method iscommonly used after retrieving a data set through a database query.

What method do you use to explicitly kill a user s session?You can dump (Kill) the session yourself by calling the method Session.Abandon.

ASP.NET automatically deletes a user's Session object, dumping its contents, after it has beenidle for a configurable timeout interval. This interval, in minutes, is set in thesection of the web.config file. The default is 20 minutes.

How do you turn off cookies for one page in your site?Use Cookie.Discard property, Gets or sets the discard flag set by the server. When true, thisproperty instructs the client application not to save the Cookie on the user's hard disk when asession ends.

Which two properties are on every validation control?We have two common properties for every validation controls1. Control to Validate,2. Error Message.

What tags do you need to add within the asp:datagrid tags to bind columns manually?

< asp:DataGrid id="dgCart" AutoGenerateColumns="False" CellPadding="4" Width="448px"runat="server" >< Columns >

< asp:ButtonColumn HeaderText="SELECT" Text="SELECT" CommandName="select" >< asp:BoundColumn DataField="ProductId" HeaderText="Product ID" >< /asp:BoundColumn >< asp:BoundColumn DataField="ProductName" HeaderText="Product Name" >< asp:BoundColumn DataField="UnitPrice" HeaderText="UnitPrice" >< /asp:BoundColumn >< /Columns >< /asp:DataGrid >

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How do you create a permanent cookie?Permanent cookies are the ones that are most useful. Permanent cookies are available until aspecified expiration date, and are stored on the hard disk. The location of cookies differs witheach browser, but this doesnt matter, as this is all handled by your browser and the server. If youwant to create a permanent cookie called Name with a value of Nigel, which expires in onemonth, youd use the following codeResponse.Cookies ("Name") = "Nigel"Response.Cookies ("Name"). Expires = DateAdd ("m", 1, Now ())

What tag do you use to add a hyperlink column to the DataGrid?< asp:HyperLinkColumn >

Which method do you use to redirect the user to another page without performing a roundtrip to the client?Server.transfer

What is the transport protocol you use to call a Web service SOAP ?HTTP Protocol

Explain role based security ?Role Based Security lets you identify groups of users to allow or deny based on their role in theorganization.In Windows NT and Windows XP, roles map to names used to identify user groups.Windows defines several built-in groups, including Administrators, Users, and Guests.To allow or deny access to certain groups of users, add the element to the authorization list in your Web application's Web.config file.e.g.< authorization >

< allow roles="Domain Name\Administrators" / > < !-- Allow Administrators in domain. -- >< deny users="*" / > < !-- Deny anyone else. -- >

< /authorization >

How do you register JavaScript for webcontrols ?You can register javascript for controls using Attribtues.Add(scriptname,scripttext) method.

When do you set "" ?Identity is a webconfig declaration under System.web, which helps to control the applicationIdentity of the web applicaton. Which can be at any level(Machine,Site,application,subdirectory,or page), attribute impersonate with "true" as value specifies that client impersonation is used.

What are different templates available in Repeater,DataList and Datagrid ?Templates enable one to apply complicated formatting to each of the items displayed by acontrol.Repeater control supports five types of templates.HeaderTemplate controls how theheader of the repeater control is formatted.ItemTemplate controls the formatting of each itemdisplayed.AlternatingItemTemplate controls how alternate items are formatted and theSeparatorTemplate displays a separator between each item displyed.FooterTemplate is used for controlling how the footer of the repeater control is formatted.The DataList and Datagrid supportstwo templates in addition to the above five.SelectedItem Template controls how a selected itemis formatted and EditItemTemplate controls how an item selected for editing is formatted.

What is ViewState ? and how it is managed ?ASP.NET ViewState is a new kind of state service that developers can use to track UI state on aper-user basis. Internally it uses an an old Web programming trick-roundtripping state in a hiddenform field and bakes it right into the page-processing framework.It needs less code to write andmaintain state in your Web-based forms.

What is web.config file ?Web.config file is the configuration file for the Asp.net web application. There is one web.configfile for one asp.net application which configuresthe particular application. Web.config file is written in XML with specific tags having specificmeanings.It includes databa which includes

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connections,Session States,Error Handling,Security etc.For example :

< configuration >< appSettings >

< add key="ConnectionString"value="server=localhost;uid=sa;pwd=;database=MyDB" / >

< /appSettings >

< /configuration >

What is advantage of viewstate and what are benefits?When a form is submitted in classic ASP, all form values are cleared. Suppose you havesubmitted a form with a lot of information and the server comes back with an error. You will haveto go back to the form and correct the information. You click the back button, and whathappens.......ALL form values are CLEARED, and you will have to start all over again! The sitedid not maintain your ViewState.With ASP .NET, the form reappears in the browser windowtogether with all form values.This is because ASP .NET maintains your ViewState. TheViewState indicates the status of the page when submitted to the server.

What tags do you need to add within the asp:datagrid tags to bind columns manually?

Set AutoGenerateColumns Property to false on the datagrid tag and then use Column tag and anASP:databound tag

< asp:DataGrid runat="server" id="ManualColumnBinding" AutoGenerateColumns="False" >< Columns >

< asp:BoundColumn HeaderText="Column1" DataField="Column1"/ >< asp:BoundColumn HeaderText="Column2" DataField="Column2"/ >

< /Columns >< /asp:DataGrid > Which property on a Combo Box do you set with a column name, prior to

setting the DataSource, to display data in the combo box?DataTextField and DataValueField

Which control would you use if you needed to make sure the values in two differentcontrols matched?CompareValidator is used to ensure that two fields are identical.

What is validationsummary server control?where it is used?.The ValidationSummary control allows you to summarize the error messages from all validationcontrols on a Web page in a single location. The summary can be displayed as a list, a bulletedlist, or a single paragraph, based on the value of the DisplayMode property. The error messagedisplayed in the ValidationSummary control for each validation control on the page is specified bythe ErrorMessage property of each validation control. If the ErrorMessage property of thevalidation control is not set, no error message is displayed in the ValidationSummary control for that validation control. You can also specify a custom title in the heading section of theValidationSummary control by setting the HeaderText property.You can control whether the ValidationSummary control is displayed or hidden by setting theShowSummary property. The summary can also be displayed in a message box by setting theShowMessageBox property to true.

What is the sequence of operation takes place when a page is loaded?BeginTranaction - only if the request is transactedInit - every time a page is processedLoadViewState - Only on postbackProcessPostData1 - Only on postbackLoad - every time

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ProcessData2 - Only on PostbackRaiseChangedEvent - Only on PostbackRaisePostBackEvent - Only on PostbackPreRender - everytimeBuildTraceTree - only if tracing is enabledSaveViewState - every timeRender - EverytimeEnd Transaction - only if the request is transacted

Trace.EndRequest - only when tracing is enabledUnloadRecursive - Every request

Difference between asp and asp.net?."ASP (Active Server Pages) and ASP.NET are both server side technologies for building websites and web applications, ASP.NET is Managed compiled code - asp is interpreted. andASP.net is fully Object oriented. ASP.NET has been entirely re-architected to provide a highlyproductive programming experience based on the .NET Framework, and a robust infrastructurefor building reliable and scalable webapplications."

Name the validation control available in asp.net?.RequiredField, RangeValidator,RegularExpression,Custom validator,compare Validator

What are the various ways of securing a web site that could prevent from hacking etc .. ?1) Authentication/Authorization2) Encryption/Decryption3) Maintaining web servers outside the corporate firewall. etc.,

What is the difference between in-proc and out-of-proc?An inproc is one which runs in the same process area as that of the client giving tha advantage of speed but the disadvantage of stability becoz if it crashes it takes the client application also withit.Outproc is one which works outside the clients memory thus giving stability to the client, but wehave to compromise a bit on speed.

When youre running a component within ASP.NET, what process is it running within onWindows XP? Windows 2000? Windows 2003?On Windows 2003 (IIS 6.0) running in native mode, the component is running within thew3wp.exe process associated with the application pool which has been configured for the webapplication containing the component.

On Windows 2003 in IIS 5.0 emulation mode, 2000, or XP, it's running within the IIS helper process whose name I do not remember, it being quite a while since I last used IIS 5.0.

What does aspnet_regiis -i do ?Aspnet_regiis.exe is The ASP.NET IIS Registration tool allows an administrator or installationprogram to easily update the script maps for an ASP.NET application to point to the ASP.NETISAPI version associated with the tool. The tool can also be used to display the status of allinstalled versions of ASP. NET, register the ASP.NET version coupled with the tool, create client-script directories, and perform other configuration operations. When multiple versions of the .NET Framework are executing side-by-side on a single computer,the ASP.NET ISAPI version mapped to an ASP.NET application determines which version of thecommon language runtime is used for the application.

The tool can be launched with a set of optional parameters. Option "i" Installs the version of ASP.NET associated with Aspnet_regiis.exe and updates the script maps at the IIS metabaseroot and below. Note that only applications that are currently mapped to an earlier version of ASP.NET are affected

What is a PostBack?The process in which a Web page sends data back to the same page on the server.

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What is ViewState? How is it encoded? Is it encrypted? Who uses ViewState?ViewState is the mechanism ASP.NET uses to keep track of server control state values that don'totherwise post back as part of the HTTP form. ViewState Maintains the UI State of a Page

ViewState is base64-encoded.It is not encrypted but it can be encrypted by setting EnableViewStatMAC="true" & setting the

machineKey validation type to 3DES. If you want to NOT maintain the ViewState, include thedirective < %@ Page EnableViewState="false" % > at the top of an .aspx page or add theattribute EnableViewState="false" to any control.

What is the < machinekey > element and what two ASP.NET technologies is it used for?Configures keys to use for encryption and decryption of forms authentication cookie data andview state data, and for verification of out-of-process session state identification.There fore 2ASP.Net technique in which it is used are Encryption/Decryption & Verification

What three Session State providers are available in ASP.NET 1.1? What are the pros andcons of each?ASP.NET provides three distinct ways to store session data for your application: in-processsession state, out-of-process session state as a Windows service, and out-of-process sessionstate in a SQL Server database. Each has it advantages.

1.In-process session-state mode

Limitations:* When using the in-process session-state mode, session-state data is lost if aspnet_wp.exe or the application domain restarts.* If you enable Web garden mode in the < processModel > element of the application's

Web.config file, do not use in-process session-state mode. Otherwise, random data loss canoccur.Advantage:* in-process session state is by far the fastest solution. If you are storing only small amounts of

volatile data in session state, it is recommended that you use the in-process provider.

2. The State Server simply stores session state in memory when in out-of-proc mode. In thismode the worker process talks directly to the State Server

3. SQL mode, session states are stored in a SQL Server database and the worker process talksdirectly to SQL. The ASP.NET worker processes are then able to take advantage of this simplestorage service by serializing and saving (using .NET serialization services) all objects within aclient's Session collection at the end of each Web requestBoth these out-of-process solutions are useful primarily if you scale your application across

multiple processors or multiple computers, or where data cannot be lost if a server or process isrestarted.

What is the difference between HTTP-Post and HTTP-Get?As their names imply, both HTTP GET and HTTP POST use HTTP as their underlying protocol.Both of these methods encode request parameters as name/value pairs in the HTTP request.The GET method creates a query string and appends it to the script's URL on the server thathandles the request.The POST method creates a name/value pairs that are passed in the body of the HTTP requestmessage.

Name and describe some HTTP Status Codes and what they express to the requestingclient.When users try to access content on a server that is running Internet Information Services (IIS)through HTTP or File Transfer Protocol (FTP), IIS returns a numeric code that indicates the statusof the request. This status code is recorded in the IIS log, and it may also be displayed in theWeb browser or FTP client. The status code can indicate whether a particular request issuccessful or unsuccessful and can also reveal the exact reason why a request is unsuccessful.There are 5 groups ranging from 1xx - 5xx of http status codes exists.101 - Switching protocols.200 - OK. The client request has succeeded

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302 - Object moved.400 - Bad request.500.13 - Web server is too busy.

Explain < @OutputCache% > and the usage of VaryByParam, VaryByHeader.OutputCache is used to control the caching policies of an ASP.NET page or user control. Tocache a page @OutputCache directive should be defined as follows < %@ OutputCacheDuration="100" VaryByParam="none" % >

VaryByParam: A semicolon-separated list of strings used to vary the output cache. By default,these strings correspond to a query string value sent with GET method attributes, or a parameter sent using the POST method. When this attribute is set to multiple parameters, the output cachecontains a different version of the requested document for each specified parameter. Possiblevalues include none, *, and any valid query string or POST parameter name.

VaryByHeader: A semicolon-separated list of HTTP headers used to vary the output cache.When this attribute is set to multiple headers, the output cache contains a different version of therequested document for each specified header.

What is the difference between repeater over datalist and datagrid?

The Repeater class is not derived from the WebControl class, like the DataGrid and DataList.Therefore, the Repeater lacks the stylistic properties common to both the DataGrid and DataList.What this boils down to is that if you want to format the data displayed in the Repeater, you mustdo so in the HTML markup.The Repeater control provides the maximum amount of flexibility over the HTML produced.Whereas the DataGrid wraps the DataSource contents in an HTML < table >, and the DataListwraps the contents in either an HTML < table > or < span > tags (depending on the DataList'sRepeatLayout property), the Repeater adds absolutely no HTML content other than what youexplicitly specify in the templates.While using Repeater control, If we wanted to display the employee names in a bold font we'dhave to alter the "ItemTemplate" to include an HTML bold tag, Whereas with the DataGrid or DataList, we could have made the text appear in a bold font by setting the control's ItemStyle-Font-Bold property to True.The Repeater's lack of stylistic properties can drastically add to the development time metric. For example, imagine that you decide to use the Repeater to display data that needs to be bold,centered, and displayed in a particular font-face with a particular background color. While all thiscan be specified using a few HTML tags, these tags will quickly clutter the Repeater's templates.Such clutter makes it much harder to change the look at a later date. Along with its increaseddevelopment time, the Repeater also lacks any built-in functionality to assist in supporting paging,editing, or editing of data. Due to this lack of feature-support, the Repeater scores poorly on theusability scale.

However, The Repeater's performance is slightly better than that of the DataList's, and is morenoticeably better than that of the DataGrid's. Following figure shows the number of requests per second the Repeater could handle versus the DataGrid and DataList

Can we handle the error and redirect to some pages using web.config?

Yes, we can do this, but to handle errors, we must know the error codes; only then we can takethe user to a proper error message page, else it may confuse the user.CustomErrors Configuration section in web.config file:The default configuration is:< customErrors mode="RemoteOnly" defaultRedirect="Customerror.aspx" >

< error statusCode="404" redirect="Notfound.aspx" / >< /customErrors >If mode is set to Off, custom error messages will be disabled. Users will receive detailedexception error messages.If mode is set to On, custom error messages will be enabled.If mode is set to RemoteOnly, then users will receive custom errors, but users accessing the site

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locally will receive detailed error messages.Add an < error > tag for each error you want to handle. The error tag will redirect the user to theNotfound.aspx page when the site returns the 404 (Page not found) error.

[Example]

There is a page MainForm.aspx

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs)Handles MyBase.Load

'Put user code to initialize the page hereDim str As System.Text.StringBuilder str.Append("hi") ' Error Line as str is not instantiatedResponse.Write(str.ToString)End Sub

[Web.Config]

< customErrors mode="On" defaultRedirect="Error.aspx"/ >

' a simple redirect will take the user to Error.aspx [user defined] error file.

< customErrors mode="RemoteOnly" defaultRedirect="Customerror.aspx" >< error statusCode="404" redirect="Notfound.aspx" / >

< /customErrors >'This will take the user to NotFound.aspx defined in IIS.

How do you implement Paging in .Net?

The DataGrid provides the means to display a group of records from the data source (for example, the first 10), and then navigate to the "page" containing the next 10 records, and so onthrough the data.

Using Ado.Net we can explicit control over the number of records returned from the data source,as well as how much data is to be cached locally in the DataSet.1.Using DataAdapter.fill method give the value of 'Maxrecords' parameter (Note: - Don't use it because query will return all records but fill the dataset based on value of 'maxrecords' parameter).2.For SQL server database, combines a WHERE clause and a ORDER BY clause with TOPpredicate.3.If Data does not change often just cache records locally in DataSet and just take some recordsfrom the DataSet to display.

What is the difference between Server.Transfer and Response.Redirect?

Server.Transfer() : client is shown as it is on the requesting page only, but the all the content is of the requested page. Data can be persist across the pages using Context.Item collection, which isone of the best way to transfer data from one page to another keeping the page state alive.

Response.Dedirect() :client knows the physical location (page name and query string as well).Context.Items loses the persistence when navigate to destination page. In earlier versions of IIS,if we wanted to send a user to a new Web page, the only option we had was Response.Redirect.While this method does accomplish our goal, it has several important drawbacks. The biggestproblem is that this method causes each page to be treated as a separate transaction. Besidesmaking it difficult to maintain your transactional integrity, Response.Redirect introduces someadditional headaches. First, it prevents good encapsulation of code. Second, you lose access toall of the properties in the Request object. Sure, there are workarounds, but they're difficult.Finally, Response.Redirect necessitates a round trip to the client, which, on high-volume sites,causes scalability problems. As you might suspect, Server.Transfer fixes all of these problems. It

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does this by performing the transfer on the server without requiring a roundtrip to theclient.Response.Redirect sends a response to the client browser instructing it to request the secondpage. This requires a round-trip to the client, and the client initiates the Request for the secondpage. Server.Transfer transfers the process to the second page without making a round-trip tothe client. It also transfers the HttpContext to the second page, enabling the second page accessto all the values in the HttpContext of the first page.

Can you create an app domain?

Yes, We can create user app domain by calling on of the following overload static methods of theSystem.AppDomain class1. Public static AppDomain CreateDomain(String friendlyName)2. Public static AppDomain CreateDomain(String friendlyName, Evidence securityInfo)3. Public static AppDomain CreateDomain(String friendlyName, Evidence securityInfo,AppDomainSetup info)4. Public static AppDomain CreateDomain(String friendlyName, Evidence securityInfo, StringappBasePath, String appRelativeSearchPath, bool shadowCopyFiles)

What are the various security methods which IIS Provides apart from .NET ?

The various security methods which IIS provides are

a) Authentication Modesb) IP Address and Domain Name Restrictionc) DNS Lookups DNS Lookupsd) The Network ID and Subnet Maske) SSL

What is Web Gardening? How would using it affect a design?

The Web Garden ModelThe Web garden model is configurable through the section of the machine.config file. Notice thatthe section is the only configuration section that cannot be placed in an application-specificweb.config file. This means that the Web garden mode applies to all applications running on themachine. However, by using the node in the machine.config source, you can adapt machine-widesettings on a per-application basis.

Two attributes in the section affect the Web garden model. They are webGarden and cpuMask.The webGarden attribute takes a Boolean value that indicates whether or not multiple worker processes (one per each affinitized CPU) have to be used. The attribute is set to false by default.The cpuMask attribute stores a DWORD value whose binary representation provides a bit maskfor the CPUs that are eligible to run the ASP.NET worker process. The default value is -1(0xFFFFFF), which means that all available CPUs can be used. The contents of the cpuMask

attribute is ignored when the webGarden attribute is false. The cpuMask attribute also sets anupper bound to the number of copies of aspnet_wp.exe that are running.

Web gardening enables multiple worker processes to run at the same time. However, you shouldnote that all processes will have their own copy of application state, in-process session state,ASP.NET cache, static data, and all that is needed to run applications. When the Web gardenmode is enabled, the ASP.NET ISAPI launches as many worker processes as there are CPUs,each a full clone of the next (and each affinitized with the corresponding CPU). To balance theworkload, incoming requests are partitioned among running processes in a round-robin manner.Worker processes get recycled as in the single processor case. Note that ASP.NET inherits anyCPU usage restriction from the operating system and doesn't include any custom semantics for doing this.

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All in all, the Web garden model is not necessarily a big win for all applications. Themore stateful applications are, the more they risk to pay in terms of real performance. Workingdata is stored in blocks of shared memory so that any changes entered by a process areimmediately visible to others. However, for the time it takes to service a request, working data iscopied in the context of the process. Each worker process, therefore, will handle its own copy of working data, and the more stateful the application, the higher the cost in performance. In thiscontext, careful and savvy application benchmarking is an absolute must.

Changes made to the section of the configuration file are effective only after IIS is restarted. In IIS6, Web gardening parameters are stored in the IIS metabase; the webGarden and cpuMaskattributes are ignored.

What is view state?.where it stored?.can we disable it?The web is state-less protocol, so the page gets instantiated, executed, rendered and thendisposed on every round trip to the server. The developers code to add "statefulness" to the pageby using Server-side storage for the state or posting the page to itself. When require to persistand read the data in control on webform, developer had to read the values and store them inhidden variable (in the form), which were then used to restore the values. With advent of .NETframework, ASP.NET came up with ViewState mechanism, which tracks the data values of server controls on ASP.NET webform. In effect,ViewState can be viewed as "hidden variable managedby ASP.NET framework!". When ASP.NET page is executed, data values from all server controls

on page are collected and encoded as single string, which then assigned to page's hiddenatrribute "< input type=hidden >", that is part of page sent to the client.

ViewState value is temporarily saved in the client's browser.ViewState can be disabled for asingle control, for an entire page orfor an entire web application. The syntax is:

Disable ViewState for control (Datagrid in this example)< asp:datagrid EnableViewState="false" ... / >

Disable ViewState for a page, using Page directive< %@ Page EnableViewState="False" ... % >

Disable ViewState for application through entry in web.config< Pages EnableViewState="false" ... / >

NET FrameWork FAQ's

Next >>When was .NET announced?Bill Gates delivered a keynote at Forum 2000, held June 22, 2000, outlining the .NET 'vision'. TheJuly 2000 PDC had a number of sessions on .NET technology, and delegates were given CDscontaining a pre-release version of the .NET framework/SDK and Visual Studio.NET. When was the first version of .NET released?The final version of the 1.0 SDK and runtime was made publicly available around 6pm PST on

15-Jan-2002. At the same time, the final version of Visual Studio.NET was made available toMSDN subscribers. What platforms does the .NET Framework run on?The runtime supports Windows XP, Windows 2000, NT4 SP6a and Windows ME/98. Windows 95is not supported. Some parts of the framework do not work on all platforms - for example,ASP.NET is only supported on Windows XP and Windows 2000. Windows 98/ME cannot be usedfor development.IIS is not supported on Windows XP Home Edition, and so cannot be used to host ASP.NET.However, the ASP.NET Web Matrixweb server does run on XP Home.The Mono project is attempting to implement the .NET framework on Linux.

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Using reflection to access .NET metadata is very similar to using ITypeLib/ITypeInfo toaccess type library data in COM, and it is used for similar purposes - e.g. determining data typesizes for marshaling data across context/process/machine boundaries.Reflection can also be used to dynamically invoke methods (see System.Type.InvokeMember ) ,or even create types dynamically at run-time (see System.Reflection.Emit.TypeBuilder).

What is the difference between Finalize and Dispose (Garbage collection) ?Class instances often encapsulate control over resources that are not managed by the runtime,

such as window handles (HWND), database connections, and so on. Therefore, you shouldprovide both an explicit and an implicit way to free those resources. Provide implicit control byimplementing the protected Finalize Method on an object (destructor syntax in C# and theManaged Extensions for C++). The garbage collector calls this method at some point after thereare no longer any valid references to the object. In some cases, you might want to provideprogrammers using an object with the ability to explicitly release these external resources beforethe garbage collector frees the object. If an external resource is scarce or expensive, better performance can be achieved if the programmer explicitly releases resources when they are nolonger being used. To provide explicit control, implement the Dispose method provided by theIDisposable Interface. The consumer of the object should call this method when it is done usingthe object.Dispose can be called even if other references to the object are alive. Note that even when youprovide explicit control by way of Dispose, you should provide implicit cleanup using the Finalizemethod. Finalize provides a backup to prevent resources frompermanently leaking if the programmer fails to call Dispose. What is Partial Assembly References?Full Assembly reference: A full assembly reference includes the assembly's text name, version,culture, and public key token (if the assembly has a strong name). A full assembly reference isrequired if you reference any assembly that is part of the commonlanguage runtime or any assembly located in the global assembly cache. Partial Assembly reference: We can dynamically reference an assembly by providing only partialinformation, such as specifying only the assembly name. When you specify a partial assemblyreference, the runtime looks for the assembly only in the applicationdirectory.

We can make partial references to an assembly in your code one of the following ways:-> Use a method such as System.Reflection.Assembly.Load and specify only a partial reference.The runtime checks for the assembly in the application directory.-> Use the System.Reflection.Assembly.LoadWithPartialName method and specify only a partialreference. The runtime checks for the assembly in the application directory and in the globalassembly cache Changes to which portion of version number indicates an incompatible change?Major or minor. Changes to the major or minor portion of the version number indicate anincompatible change. Under this convention then, version 2.0.0.0 would be consideredincompatible with version 1.0.0.0. Examples of an incompatible change would be a change to thetypes of some method parameters or the removal of a type or method altogether. Build. The Buildnumber is typically used to distinguish between daily builds or smaller compatible releases.

Revision. Changes to the revision number are typically reserved for an incremental build neededto fix a particular bug. You'll sometimes hear this referred to as the "emergency bug fix" number in that the revision is what is often changed when a fix to a specific bug is shipped to a customer. What is side-by-side execution? Can two application one using private assembly and other using Shared assembly be stated as a side-by-side executables?Side-by-side execution is the ability to run multiple versions of an application or component on thesame computer. You can have multiple versions of the common language runtime, and multipleversions of applications and components that use a version of the runtime, on the same computer at the same time. Since versioning is only applied to shared assemblies, and not to privateassemblies, two application one using private assembly and one using shared assembly cannotbe stated as side-by-sideexecutables.

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Why string are called Immutable data Type ?The memory representation of string is an Array of Characters, So on re-assigning the new arrayof Char is formed & the start address is changed . Thus keeping the Old string in Memory for Garbage Collector to be disposed. What does assert() method do?In debug compilation, assert takes in a Boolean condition as a parameter, and shows the error dialog if the condition is false. The program proceeds without any interruption if the condition istrue. What's the difference between the Debug class and Trace class?Documentation looks the same. Use Debug class for debug builds, use Trace class for bothdebug and release builds. Why are there five tracing levels in System.Diagnostics.TraceSwitcher?The tracing dumps can be quite verbose. For applications that are constantly running you run therisk of overloading the machine and the hard drive. Five levels range from None to Verbose,allowing you to fine-tune the tracing activities. Where is the output of TextWriterTraceListener redirected?To the Console or a text file depending on the parameter passed to the constructor. How do assemblies find each other?By searching directory paths. There are several factors which can affect the path (such as theAppDomain host, and application configuration files), but for private assemblies the search path isnormally the application's directory and its sub-directories. For shared assemblies, the searchpath is normally same as the private assembly path plus the shared assembly cache. How does assembly versioning work?Each assembly has a version number called the compatibility version. Also each reference to anassembly (from another assembly) includes both the name and version of the referencedassembly.The version number has four numeric parts (e.g. 5.5.2.33). Assemblies with either of the first two parts different are normally viewed as incompatible. If the first two parts are thesame, but the third is different, the assemblies are deemed as 'maybe compatible'. If only thefourth part is different, the assemblies are deemed compatible. However, this is just the defaultguideline - it is the version policy that decides to what extent these rules are enforced. Theversion policy can be specified via the application configuration file. What is garbage collection?Garbage collection is a system whereby a run-time component takes responsibility for managingthe lifetime of objects and the heap memory that they occupy. This concept is not new to .NET -Java and many other languages/runtimes have used garbage collection for some time. Why doesn't the .NET runtime offer deterministic destruction?Because of the garbage collection algorithm. The .NET garbage collector works by periodically

running through a list of all the objects that are currently being referenced by an application. Allthe objects that it doesn't find during this search are ready to be destroyed and the memoryreclaimed. The implication of this algorithm is that the runtime doesn't get notified immediatelywhen the final reference on an object goes away - it only finds out during the next sweep of theheap.Futhermore, this type of algorithm works best by performing the garbage collection sweep asrarely as possible. Normally heap exhaustion is the trigger for a collection sweep. Is the lack of deterministic destruction in .NET a problem?It's certainly an issue that affects component design. If you have objects that maintain expensiveor scarce resources (e.g. database locks), you need to provide some way for the client to tell theobject to release the resource when it is done. Microsoft recommend that you provide a methodcalled Dispose() for this purpose. However, this causes problems for distributed objects - in a

distributed system who calls the Dispose() method? Some form of reference-counting or

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ownership-management mechanism is needed to handle distributed objects - unfortunately theruntime offers no help with this.

What is serialization?Serialization is the process of converting an object into a stream of bytes. Deserialization is theopposite process of creating an object from a stream of bytes. Serialization / Deserialization ismostly used to transport objects (e.g. during remoting), or to persistobjects (e.g. to a file or database).

Does the .NET Framework have in-built support for serialization?There are two separate mechanisms provided by the .NET class library - XmlSerializer andSoapFormatter/BinaryFormatter. Microsoft uses XmlSerializer for Web Services, and usesSoapFormatter/BinaryFormatter for remoting. Both are available for use in your own code. Can I customise the serialization process?Yes. XmlSerializer supports a range of attributes that can be used to configure serialization for aparticular class. For example, a field or property can be marked with the [XmlIgnore] attribute toexclude it from serialization. Another example is the [XmlElement]attribute, which can be used to specify the XML element name to be used for a particular propertyor field.Serialization via SoapFormatter/BinaryFormatter can also be controlled to some extent by

attributes. For example, the [NonSerialized] attribute is the equivalent of XmlSerializer's[XmlIgnore] attribute. Ultimate control of the serialization process can be acheived byimplementing the the ISerializable interface on the class whose instances are to be serialized. Why is XmlSerializer so slow?There is a once-per-process-per-type overhead with XmlSerializer. So the first time you serializeor deserialize an object of a given type in an application, there is a significant delay. This normallydoesn't matter, but it may mean, for example, that XmlSerializer is a poor choice for loadingconfiguration settings during startup of a GUI application. Why do I get errors when I try to serialize a Hashtable?XmlSerializer will refuse to serialize instances of any class that implements IDictionary, e.g.Hashtable. SoapFormatter and BinaryFormatter do not have this restriction.

What are attributes?There are at least two types of .NET attribute. The first type I will refer to as a metadata attribute -it allows some data to be attached to a class or method. This data becomes part of the metadatafor the class, and (like other class metadata) can be accessed via reflection.The other type of attribute is a context attribute. Context attributes use a similar syntax tometadata attributes but they are fundamentally different. Context attributes provide aninterception mechanism whereby instance activation and method calls can bepre- and/or post-processed.

How does CAS work?The CAS security policy revolves around two key concepts - code groups and permissions.Each .NET assembly is a member of a particular code group, and each code group is granted thepermissions specified in a named permission set.For example, using the default security policy, a control downloaded from a web site belongs tothe 'Zone - Internet' code group, which adheres to the permissions defined by the 'Internet'named permission set. (Naturally the 'Internet' named permission set represents a very restrictiverange of permissions.)

Who defines the CAS code groups?Microsoft defines some default ones, but you can modify these and even create your own. To seethe code groups defined on your system, run 'caspol -lg' from the command-line. On my system itlooks like this:Level = MachineCode Groups:

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1. All code: Nothing1.1. Zone - MyComputer: FullTrust

1.1.1. Honor SkipVerification requests: SkipVerification1.2. Zone - Intranet: LocalIntranet1.3. Zone - Internet: Internet1.4. Zone - Untrusted: Nothing1.5. Zone - Trusted: Internet1.6. StrongName - 0024000004800000940000000602000000240000525341310004000003

000000CFCB3291AA715FE99D40D49040336F9056D7886FED46775BC7BB5430BA4444FEF8348EBD06F962F39776AE4DC3B7B04A7FE6F49F25F740423EBF2C0B89698D8D08AC48D69CED0FC8F83B465E0807AC11EC1DCC7D054E807A43336DDE408A5393A48556123272CEEEE72F1660B71927D38561AABF5CAC1DF1734633C602F8F2D5:Note the hierarchy of code groups - the top of the hierarchy is the most general ('All code'), whichis then sub-divided into severalgroups, each of which in turn can be sub-divided. Also note that (somewhat counter-intuitively) asub-group can be associated with a more permissive permission set than its parent. How do I define my own code group?Use caspol. For example, suppose you trust code from www.mydomain.com and you want it havefull access to your system, but you want to keep the default restrictions for all other internet sites.To achieve this, you would add a new code group as a sub-group of the'Zone - Internet' group, like this:caspol -ag 1.3 -site www.mydomain.com FullTrustNow if you run caspol -lg you will see that the new group has been added as group 1.3.1:

1.3. Zone - Internet: Internet1.3.1. Site - www.mydomain.com : FullTrust

Note that the numeric label (1.3.1) is just a caspol invention to make the code groups easy tomanipulate from the command-line. The underlying runtime never sees it.

How do I change the permission set for a code group?Use caspol. If you are the machine administrator, you can operate at the 'machine' level - whichmeans not only that the changes you make become the default for the machine, but also thatusers cannot change the permissions to be more permissive. If you are a normal (non-admin)user you can still modify the permissions, but only to make them more restrictive. For example, toallow intranet code to do what it likes you might do this:caspol -cg 1.2 FullTrustNote that because this is more permissive than the default policy (on a standard system), youshould only do this at the machine level - doing it at the user level will have no effect. I can't be bothered with all this CAS stuff. Can I turn it off?Yes, as long as you are an administrator. Just run: caspol -s off Can I look at the IL for an assembly?Yes. MS supply a tool called Ildasm which can be used to view the metadata and IL for anassembly. Can source code be reverse-engineered from IL?Yes, it is often relatively straightforward to regenerate high-level source (e.g. C#) from IL. How can I stop my code being reverse-engineered from IL?There is currently no simple way to stop code being reverse-engineered from IL. In future it islikely that IL obfuscation tools will become available, either from MS or from third parties. Thesetools work by 'optimising' the IL in such a way that reverse-engineering becomes much moredifficult.

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Of course if you are writing web services then reverse-engineering is not a problem as clientsdo not have access to your IL. Is there built-in support for tracing/logging?Yes, in the System.Diagnostics namespace. There are two main classes that deal with tracing -Debug and Trace. They both work in a similar way - the difference is that tracing from the Debugclass only works in builds that have the DEBUG symbol defined, whereas tracing from the Traceclass only works in builds that have the TRACE symbol defined. Typically this means that you

should use System.Diagnostics.Trace.WriteLine for tracing that you want to work in debug andrelease builds, and System.Diagnostics.Debug.WriteLine for tracing that you want to work only indebug builds. Can I redirect tracing to a file?Yes. The Debug and Trace classes both have a Listeners property, which is a collection of sinksthat receive the tracing that you send via Debug.WriteLine and Trace.WriteLine respectively. Bydefault the Listeners collection contains a single sink, which is aninstance of the DefaultTraceListener class. This sends output to the Win32 OutputDebugString()function and also the System.Diagnostics.Debugger.Log() method. This is useful whendebugging, but if you're trying to trace a problem at a customer site, redirecting the output to a fileis more appropriate. Fortunately, the TextWriterTraceListener class is provided for this purpose. What are the contents of assembly?In general, a static assembly can consist of four elements:The assembly manifest, which contains assembly metadata.Type metadata.Microsoft intermediate language (MSIL) code that implements the types.

A set of resources.

What is GC (Garbage Collection) and how it worksOne of the good features of the CLR is Garbage Collection, which runs in the backgroundcollecting unused object references, freeing us from having to ensure we always destroy them. Inreality the time difference between you releasing the object instance and it being garbagecollected is likely to be very small, since the GC is always running.[The process of transitively tracing through all pointers to actively used objects in order to locate

all objects that can be referenced, and then arranging to reuse any heap memory that was notfound during this trace. The common language runtime garbage collector also compacts thememory that is in use to reduce the working space needed for the heap.] Heap:A portion of memory reserved for a program to use for the temporary storage of data structureswhose existence or size cannot be determined until the program is running.

Differnce between Managed code and unmanaged code ?Managed Code:Code that runs under a "contract of cooperation" with the common language runtime. Managedcode must supply the metadata necessary for the runtime to provide services such as memorymanagement, cross-language integration, code access security, andautomatic lifetime control of objects. All code based on Microsoft intermediate language (MSIL)executes as managed code.

Un-Managed Code:Code that is created without regard for the conventions and requirements of the commonlanguage runtime. Unmanaged code executes in the common language runtime environment withminimal services (for example, no garbage collection, limited debugging, and so on). What is MSIL, IL, CTS and, CLR ? MSIL: (Microsoft intermediate language)When compiling to managed code, the compiler translates your source code into Microsoftintermediate language (MSIL), which is a CPU-independent set of instructions that can be

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efficiently converted to native code. MSIL includes instructions for loading, storing,initializing, and calling methods on objects, as well as instructions for arithmetic and logicaloperations, control flow, direct memory access, exception handling, and other operations. Beforecode can be executed, MSIL must be converted to CPU-specific code, usually by a just-in-time(JIT) compiler. Because the common language runtime supplies one or more JIT compilers for each computer architecture it supports, the same set of MSIL can be JIT-compiled and executedon any supported architecture.When a compiler produces MSIL, it also produces metadata. Metadata describes the types in

your code, including the definition of each type, the signatures of each type's members, the members that your code references, andother data that the runtime uses atexecution time. The MSIL and metadata are contained in a portable executable (PE) file that isbased on and extends the publishedMicrosoft PE and Common Object File Format (COFF) used historically for executable content.This file format, which accommodates

MSIL or native code as well as metadata, enables the operating system to recognize commonlanguage runtime images. Thepresence of metadata in the file along with the MSIL enables your code to describe itself, whichmeans that there is no need for type libraries or Interface Definition Language (IDL). The runtimelocates and extracts the metadata from the file as needed duringexecution.

IL: (Intermediate Language)A language used as the output of a number of compilers and as the input to a just-in-time (JIT)compiler. The common languageruntime includes a JIT compiler for converting MSIL to native code. CTS: (Common Type System)The specification that determines how the common language runtime defines, uses, andmanages types CLR: (Common Language Runtime)The engine at the core of managed code execution. The runtime supplies managed code with

services such as cross-languageintegration, code access security, object lifetime management, and debugging and profilingsupport.

What is Reference type and value type ?Reference Type:Reference types are allocated on the managed CLR heap, just like object types.A data type that is stored as a reference to the value's location. The value of a reference type isthe location of the sequence of bitsthat represent the type's data. Reference types can be self-describing types, pointer types, or interface types Value Type:

Value types are allocated on the stack just like primitive types in VBScript, VB6 and C/C++. Valuetypes are not instantiated using new go out of scope when the function they are defined withinreturns.Value types in the CLR are defined as types that derive from system.valueType. A data type that fully describes a value by specifying the sequence of bits that constitutes thevalue's representation. Type information for a value type instance is not stored with the instanceat run time, but it is available in metadata. Value type instances can be treated as objects usingboxing. What is Boxing and unboxing ?Boxing:The conversion of a value type instance to an object, which implies that the instance will carry full

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type information at run time and will be allocated in the heap. The Microsoftintermediate language (MSIL) instruction set's box instruction converts a value type to an objectby making a copy of the value type and embedding it in a newly allocated object. Un-Boxing:The conversion of an object instance to a value type.What is JIT and how is works ?An acronym for "just-in-time," a phrase that describes an action that is taken only when it

becomes necessary, such as just-in-time compilation or just-in-time object activation What is portable executable (PE) ?The file format used for executable programs and for files to be linked together to form executableprograms What is strong name?A name that consists of an assembly's identityits simple text name, version number, and cultureinformation (if provided)strengthened by a public key and a digital signature generated over theassembly. Because the assembly manifestcontains file hashes for all the files that constitute the assembly implementation, it is sufficient togenerate the digital signature over just the one file in the assembly that contains the assemblymanifest. Assemblies with the same strong name are expected to be identical

What is global assembly cache?A machine-wide code cache that stores assemblies specifically installed to be shared by manyapplications on the computer. Applications deployed in the global assembly cache must have astrong name. What is difference between constants, readonly and, static ?Constants: The value cant be changedRead-only: The value will be initialized only once from the constructor of the class.Static: Value can be initialized once. What is difference between shared and public?An assembly that can be referenced by more than one application. An assembly must beexplicitly built to be shared by giving it a cryptographically strong name. What is namespace used for loading assemblies at run time and name the methods?System.Reflection What are the types of authentication in .net?We have three types of authentication:1. Form authentication2. Windows authentication3. PassportThis has to be declared in web.config file.

What is the difference between a Struct and a Class ?The struct type is suitable for representing lightweight objects such as Point, Rectangle, andColor. Although it is possible to represent a point as a class, a struct is more efficient in somescenarios. For example, if you declare an array of 1000 Point objects,you will allocate additional memory for referencing each object. In this case, the struct is lessexpensive.When you create a struct object using the new operator, it gets created and the appropriateconstructor is called. Unlike classes, structs can be instantiated without using the new operator. If you do not use new, the fields will remain unassigned and the object cannot be used until all of the fields are initialized. It is an error to declare a default (parameterless) constructor for a struct.A default constructor is always provided to initialize the struct members to their default values.It is an error to initialize an instance field in a struct.There is no inheritance for structs as there is for classes. A struct cannot inherit from another struct or class, and it cannot be the base of a class. Structs, however, inherit from the base class

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date and time as one of the values that won't change. This way you declare public readonlystring DateT = new DateTime().ToString().

What happens when you encounter a continue statement inside the for loop?The code for the rest of the loop is ignored, the control is transferred back to the beginning of theloop.

What's the advantage of using System.Text.StringBuilder over System.String?

StringBuilder is more efficient in the cases, where a lot of manipulation is done to the text. Stringsare immutable, so each time it's being operated on, a new instance is created.

Can you store multiple data types in System.Array?No.

What's the difference between the System.Array.CopyTo() and System.Array.Clone()?The first one performs a deep copy of the array, the second one is shallow.

How can you sort the elements of the array in descending order?By calling Sort() and then Reverse() methods.

What's the .NET datatype that allows the retrieval of data by a unique key?HashTable.

What's class SortedList underneath?A sorted HashTable.

Will finally block get executed if the exception had not occurred?Yes.

Can multiple catch blocks be executed?No, once the proper catch code fires off, the control is transferred to the finally block (if there areany), and then whatever follows the finally block.

Why is it a bad idea to throw your own exceptions?Well, if at that point you know that an error has occurred, then why not write the proper code tohandle that error instead of passing a new Exception object to the catch block? Throwing your own exceptions signifies some design flaws in the project.

What's a delegate?A delegate object encapsulates a reference to a method. In C++ they were referred to as functionpointers.

What's a multicast delegate?It's a delegate that points to and eventually fires off several methods.

How's the DLL Hell problem solved in .NET?Assembly versioning allows the application to specify not only the library it needs to run (whichwas available under Win32), but also the version of the assembly.

What are the ways to deploy an assembly?An MSI installer, a CAB archive, and XCOPY command.

What's a satellite assembly?When you write a multilingual or multi-cultural application in .NET, and want to distribute the coreapplication separately from the localized modules, the localized assemblies that modify the coreapplication are called satellite assemblies.

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What namespaces are necessary to create a localized application?System.Globalization, System.Resources.

What does assert() do?In debug compilation, assert takes in a Boolean condition as a parameter, and shows the error dialog if the condition is false. The program proceeds without any interruption if the condition istrue.

What's the difference between the Debug class and Trace class?Documentation looks the same. Use Debug class for debug builds, use Trace class for bothdebug and release builds.

Why are there five tracing levels in System.Diagnostics.TraceSwitcher?The tracing dumps can be quite verbose and for some applications that are constantly runningyou run the risk of overloading the machine and the hard drive there. Five levels range from Noneto Verbose, allowing to fine-tune the tracing activities.

Where is the output of TextWriterTraceListener redirected?To the Console or a text file depending on the parameter passed to the constructor.

What namespaces are necessary to create a localized application?System.Globalization, System.Resources.

What are three test cases you should go through in unit testing?Positive test cases (correct data, correct output), negative test cases (broken or missing data,proper handling), exception testcases (exceptions are thrown and caught properly).

Can you change the value of a variable while debugging a C# application?Yes, if you are debugging via Visual Studio.NET, just go to Immediate window.

What's the implicit name of the parameter that gets passed into the class' set method?

Value, and it's datatype depends on whatever variable we're changing.

How do you inherit from a class in C#?Place a colon and then the name of the base class. Notice that it's double colon in C++.

Does C# support multiple inheritance?No, use interfaces instead.

When you inherit a protected class-level variable, who is it available to?Derived Classes. What's the top .NET class that everything is derived from?System.Object.

How's method overriding different from overloading?When overriding, you change the method behavior for a derived class. Overloading simplyinvolves having a method with the same name within the class.

What does the keyword virtual mean in the method definition?The method can be over-ridden.

Can you declare the override method static while the original method is non-static?No, you can't, the signature of the virtual method must remain the same, only the keyword virtualis changed to keyword override.

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Can you override private virtual methods?No, moreover, you cannot access private methods in inherited classes, have to be protected inthe base class to allow any sort of access.

Can you prevent your class from being inherited and becoming a base class for someother classes?Yes, that's what keyword sealed in the class definition is for. The developer trying to derive fromyour class will get a message: cannot inherit from Sealed class WhateverBaseClassName. It's

the same concept as final class in Java.

Can you allow class to be inherited, but prevent the method from being over-ridden?Yes, just leave the class public and make the method sealed.

Why can't you specify the accessibility modifier for methods inside the interface?They all must be public. Therefore, to prevent you from getting the false impression that you haveany freedom of choice, you are not allowed to specify any accessibility, it's public by default.

Can you inherit multiple interfaces?Yes, why not.

And if they have conflicting method names?It's up to you to implement the method inside your own class, so implementation is left entirely upto you. This might cause a problem on a higher-level scale if similarly named methods fromdifferent interfaces expect different data, but as far as compiler cares you'reokay.

What's the difference between an interface and abstract class?In the interface all methods must be abstract, in the abstract class some methods can beconcrete. In the interface no accessibility modifiers are allowed, which is ok in abstract classes.

How can you overload a method?Different parameter data types, different number of parameters, different order of parameters.

If a base class has a bunch of overloaded constructors, and an inherited class has another bunch of overloaded constructors, can you enforce a call from an inherited constructor toan arbitrary base constructor?Yes, just place a colon, and then keyword base (parameter list to invoke the appropriateconstructor) in the overloaded constructor definition inside the inherited class.

What's the difference between System.String and System.StringBuilder classes?System.String is immutable, System.StringBuilder was designed with the purpose of having amutable string where a variety of operations can be performed.

Does C# support multiple-inheritance?No, use interfaces instead. When you inherit a protected class-level variable, who is it available to?The derived class. Are private class-level variables inherited?Yes, but they are not accessible. Although they are not visible or accessible via the classinterface, they are inherited. Describe the accessibility modifier "protected internal".It is available to derived classes and classes within the same Assembly (and naturally from thebase class it's declared in). What's the top .NET class that everything is derived from?System.Object.

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What's the advantage of using System.Text.StringBuilder over System.String?StringBuilder is more efficient in cases where there is a large amount of string manipulation.Strings are immutable, so each time it's being operated on, a new instance is created. Can you store multiple data types in System.Array?No. What's the .NET class that allows the retrieval of a data element using a unique key?HashTable. Will the finally block get executed if an exception has not occurred?Yes. What's an abstract class?A class that cannot be instantiated. An abstract class is a class that must be inherited and havethe methods overridden. An abstract class is essentially a blueprint for a class without anyimplementation.

When do you absolutely have to declare a class as abstract?

1. When at least one of the methods in the class is abstract.2. When the class itself is inherited from an abstract class, but not all base abstract methodshave been overridden. What's an interface?It's an abstract class with public abstract methods all of which must be implemented in theinherited classes.

Why can't you specify the accessibility modifier for methods inside the interface?They all must be public. Therefore, to prevent you from getting the false impression that youhave any freedom of choice,you are not allowed to specify any accessibility, it's public by default. What's the difference between an interface and abstract class?In an interface class, all methods must be abstract. In an abstract class some methods can beconcrete. In an interface class, no accessibility modifiers are allowed, which is ok in an abstractclass. How is method overriding different from method overloading?When overriding a method, you change the behavior of the method for the derived class.Overloading a method simply involveshaving another method with the same name within the class. Can you declare an override method to be static if the original method is non-static?No. The signature of the virtual method must remain the same, only the keyword virtual ischanged to keyword override.

Can you override private virtual methods?No. Private methods are not accessible outside the class. Can you write a class without specifying namespace? Which namespace does it belong toby default?Yes, you can, then the class belongs to global namespace which has no name. For commercialproducts, naturally, you wouldn't want global namespace.

What is a formatter?A formatter is an object that is responsible for encoding and serializing data into messages onone end, and deserializing and decoding messages into data on the other end.

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Different b/w .NET & J2EE ?Differences between J2EE and the .NET Platform

Vendor Neutrality

The .NET platform is not vendor neutral, it is tied to the Microsoft operating systems. But neither are any of the J2EE implementationsMany companies buy into J2EE believing that it will give them vendor neutrality. And, in fact, thisis a stated goal of Sun's vision:A wide variety of J2EE product configurations and implementations, all of which meet therequirements of this specification, are possible. A portable J2EE application will function

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